drm/mst: Fix error handling during MST sideband message reception

Handle any error due to partial reads, timeouts etc. to avoid parsing uninitialized data subsequently. Also bail out if the parsing itself fails. Cc: Dave Airlie <[email protected]> Cc: Lyude <[email protected]> Cc: Daniel Vetter <[email protected]> Signed-off-by: Imre Deak <[email protected]> Reviewed-by: Lyude <[email protected]> Cc: [email protected] Signed-off-by: Daniel Vetter <[email protected]> Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
gibsson · Jul 20, 2017 · 448421b · 448421b
1 parent ef434a0
commit 448421b
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2196,11 +2196,17 @@ static void drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
 		ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
 				    replyblock, len);
 		if (ret != len) {
-			DRM_DEBUG_KMS("failed to read a chunk\n");
+			DRM_DEBUG_KMS("failed to read a chunk (len %d, ret %d)\n",
+				      len, ret);
+			return;
 		}
+
 		ret = drm_dp_sideband_msg_build(msg, replyblock, len, false);
-		if (ret == false)
+		if (!ret) {
 			DRM_DEBUG_KMS("failed to build sideband msg\n");
+			return;
+		}
+
 		curreply += len;
 		replylen -= len;
 	}